Fix drop path being ignored in DINOv2

[fepegar]

What does this PR do?

A drop_path_rate parameter exists in the DINOv2 model, which is propagated all the way to the DINOv2 layers, but never used. This PR addresses this by using the drop path layers in the forward pass of the DINOv2 layers, and removing an (I think) unnecessary extra instantiation.

Fixes #29140.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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• Did you write any new necessary tests?

Who can review?

@amyeroberts @NielsRogge @molbap

[amyeroberts]

Thanks for fixing this!

[fepegar]

Thanks for reviewing, @amyeroberts!